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The endotoxin-liberating effect of antibiotics on meningococci in vitro
Abstract:
Three strains of Neisseria meningitis (two endotoxin-liberating and one in vitro variant non-liberating) were studied during treatment with MIC and 100 times MIC values of benzylpenicillin and chloramphenicol in a chemically-defined, protein-free medium. Treatment with the highest dose of benzylpenicillin had the most rapid effect on meningococci, although the antibacterial effect was the same for the two penicillin concentrations after 20 h. Chloramphenicol treatment showed a much slower antibacterial effect. After 2 h of antibacterial treatment, an increase of filtrable endotoxin in the medium was found for the endotoxin-ligerating strains only when the highest penicillin dose was used. During the same period there was a rapid cell death. After 20 hours of treatment, however, the endotoxin-liberating strains treated with high and low concentrations of penicillin had a markedly reduced content of filtrable endotoxin, compared to the controls and to the cultures treated with chloramphenicol. Antibacterial treatment had no, or only minimal, effect on the total content of endotoxin in the cultures, compared to the untreated controls. The endotoxin non-liberating strain had about the same total content of endotoxin as the liberating strains, but did not liberate filtrable endotoxin into the medium unless filtered with a much higher pressure through a filter with smaller pore size.
Insights
Benzylpenicillin rapidly reduced endotoxin-liberating Neisseria meningitidis, decreasing filtrable endotoxin. Chloramphenicol showed slower effects, with no significant impact on total endotoxin levels.
Area of Science:
- Microbiology
- Bacteriology
- Pharmacology
Background:
- Neisseria meningitidis causes meningitis, a serious infection.
- Bacterial endotoxins contribute to disease pathogenesis.
- Understanding antibiotic effects on endotoxin release is crucial for treatment.
Purpose of the Study:
- To investigate the impact of benzylpenicillin and chloramphenicol on endotoxin release from Neisseria meningitidis.
- To compare the efficacy of these antibiotics in vitro.
Main Methods:
- Three Neisseria meningitidis strains (two endotoxin-liberating, one non-liberating) were cultured.
- Cultures were treated with benzylpenicillin or chloramphenicol at Minimum Inhibitory Concentration (MIC) and 100x MIC.
- Filtrable and total endotoxin levels were measured over time.
Main Results:
- Benzylpenicillin demonstrated a rapid antibacterial effect, with higher doses initially increasing filtrable endotoxin in some strains.
- After 20 hours, benzylpenicillin significantly reduced filtrable endotoxin in treated strains.
- Chloramphenicol exhibited a slower antibacterial effect and did not reduce filtrable endotoxin.
- Total endotoxin content was largely unaffected by either antibiotic treatment.
Conclusions:
- Benzylpenicillin is more effective than chloramphenicol in reducing endotoxin release from Neisseria meningitidis in vitro.
- Antibiotic choice may influence endotoxin-related complications in meningococcal infections.